USPTO Patents Application 09843941

Attorney Docket No.: 06530.0278

UNITED STATES PATENT APPLICATION
FOR

ENDOSCOPIC STENT DELIVERY SYSTEM AND METHOD

BY

JAMES F. HEMERICK
AND
ERIC SCHNEIDER

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Finn eg an, Henderson,
Farabow, Garrett,
s dunner, l.l.p.

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Finn eg an ; Henderson,
Farabow, Garrett ;
S Dunner, l l.p.

1300 I STREET, N. W.
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DESCRIPTION OF THE INVENTION

Field of the Invention

[001] The present invention relates to stent delivery systems and methods.
More particularly, the present invention relates to endoscopic stent delivery systems
and methods.

Background of the Invention

[002] Medical stents may be used in a variety of medical procedures. Such
stents may be used to provide structural support to an anatomical structure, such as a
fluid vessel, in order to prevent the structure from collapse, widen the lumens of such
j structures to reverse an occluded state, or allow other material to be injected or
| removed through the anatomical structure. Typically, such medical stents are delivered
j to a target anatomical structure in a tissue system via stent delivery systems. These
stent delivery systems may be elongated devices that are through fluid vessels into or in
proximity to target organs or tissue systems. Once in position, an outer tubular
projection of the stent delivery system is retracted proximally while an inner portion,
which maintains a stent in its distal end, is stationed in place. This relative movement of
the outer tubular portion with respect to a stationary inner portion serves to deploy and
position the stent in place. Use of such medical stents has allowed medical personnel
to perform procedures that widen fluid vessels in a relatively rapid and non-invasive
manner.

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[003] The deployment of a stent in tortuous anatomy, such as a blood vessel
system, typically requires satisfactory force transmission with low friction interfaces.
Typically, endoscopic deployment/reconstrainment forces are maintained under 10
pounds. Conventional 7.5 French endoscopic stent delivery systems may provide a low
friction interface between inner and outer assemblies. However, the multi-layer exterior
tube may be stiff and susceptible to kinking and stretching, resulting in damage to the
delivery system during a medical procedure, thus possibly creating a hazardous
condition for the patient. Other 8 French delivery systems may use a 55D Pellethane
jacket on the inner assembly to fill the gap with the outer tube while maintaining
flexibility. This latter design may result in excessive friction between the Pellethane
jacket inner assembly and the PTFE exterior tube liner during
deployment/reconstrainment in a tortuous anatomy. During deployment and
reconstrainment, the forces required to create relative movement between the inner and
outer assemblies accumulate with the stent resistance. The resulting cumulative force
can exceed the maximum allowable force requirement for such stent delivery systems,
thus possibly resulting in damage to the stent or stent delivery system during a medical
procedure and, hence, contributing to a hazardous condition for the patient. Use of a
relatively stiff material for the outer or inner assembly of the stent delivery device may
result in kinking or breaking of the assembly, but inhibits stretching of the assembly
during deployment/reconstrainment and promotes structural integrity of the assembly.
For example, material with a durometer measure of 75D may be stiff enough to provide
structural integrity, but may be too stiff to manipulate around corners or bends.
Alternatively, use of material that is relatively soft, i.e. lower durometer material such as

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55D, may result in stretching or breakage after application of a high force, but typically
allows better tracking through tortuous anatomy because of the added flexibility.

[004] Thus, it would be advantageous for a stent delivery system to have
sufficient strength and stiffness to minimize kinking, stretching, and breakage, while at
the same time, be flexible enough to be easily led through tortuous anatomy in the
body.

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SUMMARY OF THE INVENTION

[005] The advantages and purpose of the invention will be set forth in part in the
description which follows, and in part will be obvious from the description, or may be
learned by practice of the invention. The advantages and purpose of the invention will
be realized and attained by means of the elements and combinations particularly
pointed out in the appended claims.

[006] To attain the advantages and in accordance with the purpose of the
invention, as embodied and broadly described herein, an exemplary embodiment of the
invention includes a system for delivering a stent into an anatomical structure. The
system comprises an outer tubular structure having a proximal end and a distal end and
an inner elongated structure. The inner elongated structure comprises a proximal end
and a distal end and is located within the outer tubular structure such that the distal end
of the inner elongated structure substantially coincides with the distal end of the outer
tubular structure. The inner elongated structure has a stent accommodating area on its
distal end, and an external tubular structure contact area projecting from its surface and

3

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located proximal to the stent accommodating area. The external tubular structure
contact area frictionally slides against an interior surface of the outer tubular structure.

[007] In another exemplary embodiment, there is a gap between an external
surface of the inner elongated structure and the interior surface of the outer tubular
structure.

[008] In another exemplary embodiment, the external tubular contact area on
the inner elongated structure is constructed of Pellethane.

[009] In yet another exemplary embodiment, there are a plurality of external
tubular structure contact areas, wherein each subsequent proximal external tubular
structure contact area on the surface of the inner elongated structure increases in
durometer from the distal end to the proximal end of the inner elongated structure.

[010] In another exemplary embodiment, the invention includes an inner
elongated structure for a tubular stent delivery device used in deploying a stent into an
anatomical structure. The inner elongated structure comprises an elongated structure,
a stent accommodating area on a distal end of the elongated structure and shaped to
receive a constrained length of a stent, and an engagement area projecting from the
surface of the elongated structure and located proximal to the stent accommodating
area. The engagement area is able to frictionally slide against an interior surface of an
outer tubular structure of a stent delivery device.

[01 1] In a further exemplary embodiment, the invention includes an inner
elongated structure for a tubular stent delivery device used in deploying a stent into an
anatomical structure. The inner elongated structure comprises an elongated structure,
stent accommodating means for accommodating a constrained length of a stent at a

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distal end of the elongated structure, and engagement means for frictionally engaging
the elongated structure with an interior surface of an outer tubular structure of a stent
delivery device.

[012] In another exemplary embodiment, the invention includes a method of
deploying a stent with respect to an anatomical structure. The method includes
providing a stent delivery system, wherein the system comprises an outer tubular
structure having a proximal end and a distal end, an inner elongated structure having a
proximal end and a distal end and is located within the outer tubular structure such that
the distal end of the inner elongated structure substantially coincides with the distal end
of the outer tubular structure. A stent accommodating area on the distal end of the
inner elongated structure accommodates a stent. An external tubular structure contact
area projecting from a surface of the inner elongated structure and located proximal to
the stent accommodating area slides against an interior surface of the outer tubular
structure. The method includes inserting the stent delivery system through an insertion
point in a body until the distal ends of the external tubular structure and the inner
elongated structure are in a position within the anatomical structure, and moving the
outer tubular structure proximally while maintaining the position of the inner elongated
structure, thus exposing the stent accommodating area and releasing at least part of the
stent into the anatomical structure, and continuing the proximal movement of the outer
tubular structure with respect to the inner elongated structure until the stent is
completely deployed into the anatomical structure, and withdrawing the stent delivery
system from the insertion point in the body.

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[013] In another exemplary embodiment of the method above, the stent delivery
system includes a gap between an external surface of the inner elongated structure and
the interior surface of the outer tubular structure.

[014] Additional objects and advantages of the invention will be set forth in part
in the description which follows, and in part will be obvious from the description, or may
be learned by practice of the invention. The objects and advantages of the invention
will be realized and attained by means of the elements and combinations particularly
pointed out in the appended claims.

[01 5] It is to be understood that both the foregoing general description and the
following detailed description are exemplary and explanatory only and are not restrictive
of the invention, as claimed.

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BRIEF DESCRIPTION OF THE DRAWINGS

[016] The accompanying drawings, which are incorporated in and constitute a
part of this specification, illustrate several embodiments of the invention and together
with the description, serve to explain the principles of the invention. In the drawings,

[017] Fig. 1 is a block diagram depicting the interaction of a stent delivery
system with a human body.

[018] Fig. 2a is a longitudinal cross-section showing a stent delivery system in
position within a body.

[019] Fig. 2b is a longitudinal cross-section showing a stent delivery system
during deployment of a stent into an anatomical structure within the body.

[020] Fig. 2c is a longitudinal cross-section showing a stent delivery system

t

being removed from the body after deployment of a stent into an anatomical structure in !
the body.

[021] Fig. 3 is a side elevation showing an exemplary embodiment of an outer
assembly of the stent delivery system of this invention.

[022] Fig. 4a is a side elevation of an exemplary embodiment of an inner
assembly of the stent delivery system of this invention.

[023] Fig. 4b is a planar cross-section along line A-A of the exemplary
embodiment of an inner assembly of the stent delivery system of this invention depicted j
in Fig. 4a. I
[024] Fig. 4c is a longitudinal cross-section along line B-B of the exemplary j

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embodiment of an inner assembly of the stent delivery system of this invention depicted j

in Fig. 4b. !

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[025] Fig. 5a is a fragmentary cross section showing an exemplary embodiment j

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of a portion of the inner assembly of a stent delivery system of this invention at a
junction between different types of materials.

[026] Fig. 5b is an enlarged fragmentary cross section showing an exemplary
embodiment of a portion of the outer and inner assemblies of a stent delivery system of
this invention at a junction between different types of materials.

[027] Fig. 6a is a side elevation of another exemplary embodiment of an inner
assembly of the stent delivery system of this invention.

Finnecan, Henderson, '
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[028] Fig. 6b is a planar cross-section along line A-A of the exemplary
embodiment of an inner assembly of the stent delivery system of this invention depicted
in Fig. 6a.

[029] Fig. 6c is a longitudinal cross-section along line B-B of the exemplary
embodiment of an inner assembly of the stent delivery system of this invention depicted
in Fig. 6b.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the exemplary embodiments of the invention,
examples of which are illustrated in the accompanying drawings. Wherever possible,
the same reference numbers will be used throughout the drawings to refer to the same
or like parts.

[030] The present invention includes a stent delivery system and method that
allows for easy stent delivery system manipulation through a human body while
maintaining structural stability. Furthermore, a stent delivery system according to
embodiments of this invention resists kinking and breakage by being constructed of
material and in such a configuration that resists structural compromise while being led
through tortuous body anatomy. The stent delivery system according to embodiments
of this invention also inhibits friction by minimizing the contact area between the inner
and outer assemblies, when one assembly is moving with respect to the other one of
the stent delivery device, by allowing a clearance space to exist between the two
assemblies. Furthermore, use of particularly resilient material on the inner assembly
promotes flexibility while maintaining structural stability. In another exemplary
embodiment of the invention, the inner assembly includes use of increasingly flexible

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material from the inner assembly's proximal to distal end, thus achieving greater
flexibility of the stent delivery device where the flexibility may be needed more to wind
through tortuous anatomy, closer to the distal end.

[031] One illustrative embodiment of the invention shown in Figs. 1-5 is a stent
delivery system 100, as shown in operation in Figs. 1 and 2a-2c. First, a method of
operation of the system 100 will be described with reference to Figs. 1 and 2a-2c to
facilitate the later discussion of the structural features of the system 100.

[032] The stent delivery system 100 may be divided into a generally tubular
delivery assembly 101 and a stent 102. The delivery assembly 101 typically has multi-
concentric elongated tube assemblies, which may include at least an outer tube
assembly 105, that extends a substantial length of the delivery assembly 101. The
delivery assembly 101 may also include an inner elongated structure 104, that may be a
tubular assembly, by example, that typically extends the entire length of the delivery
assembly 101, and also communicates with a stent 102 that is in contact with its distal
end. The stent 102 may be a braided metallic, polymeric, or other suitable stent that
typically is maintained in a stressed, compressed, and elongated state within the outer
assembly 105 and is movable by the inner assembly 104. The stent 102, once placed
in position into an anatomical structural 191, in a process called deployment, may act as
a structural framework in maintaining the geometry of the anatomical structure 191.
This interaction of the stent 1 02 with the outer tube and inner tube assemblies, 1 05 and
104, respectively, will be discussed in more detail below. Furthermore, the relative
terms, proximal and distal, as used herein and throughout the specification, will be given

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its conventional medical definition in that proximal means relatively further away from
the body and distal means relatively further into the body.

[033] As shown in Fig. 1 , the tubular delivery assembly 101 may be introduced
into a patient's body 190 through an insertion point 192, which may be a natural orifice,
such as the esophagus, for example, or a suitable invasive insertion point, such as
through a suitable incision in the skin, as deemed by a health care worker. Most
endoscopic devices are inserted through an endoscope. After introducing the delivery
assembly 101 into the patient 190 through insertion point 192, the health care worker
would direct the delivery assembly 101 through the natural internal anatomy of the
patient until the distal end of the delivery assembly reaches a pre-determined target
area, such as the anatomical structure 191. An anatomical structure 191 may include
blood vessels, such as the aorta or coronary blood vessels, enzyme vessels, such as
the bile duct, colonic structures and the like, or other suitable anatomical structure that
may need to have a stent 102 positioned within for appropriate medical reasons.

[034] As shown in Fig. 2a, when the stent delivery assembly 101 has been
positioned into a pre-determined suitable position in the body 190, with its distal end
103a located within or in desired proximity to a target anatomical structure 191,
deployment of the stent 102 may be initiated. The delivery assembly 101 typically has
an inner assembly 104 and an outer assembly 105. The inner assembly 104 is usually
longer than the outer assembly 105, but not necessarily. The inner assembly 104 may
be an elongated structure, such as a tube with an interior that opens at both its distal
end 104d and its proximal end 104p to allow for guidewire access or communication of
fluids through the inner assembly 104. Such fluids that may be communicated through

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the inner assembly may include enzymes that may destroy structures, such as
physiological stones, that block the passages of fluid vessels. Furthermore, an injection
port 106, controllable by a shut-off valve 107, may allow for desired fluids to be
introduced into the narrow gap space 108 between exterior surface of the interior
assembly 1 04 and the interior surface of the outer assembly 1 05. Fluids that may be
introduced through injection port 106 may include lubricating fluids to promote relative
movement of the inner and outer assemblies with respect to each other. Additional
structures that may be included on the stent delivery system 100 include a handling
structure 1 16 to allow a health care worker to easily move the inner 104 and outer 105
yg assemblies with respect to each other, and a lead point 117, typically conical, that

I eases the directional movement of the delivery assembly 1 01 through body anatomy.

: | [035] Deployment of the stent 102, as shown in Fig. 2b, may be initiated by

holding steady the inner assembly 104 while moving the outer assembly 105 proximally
]£ in the direction of the arrow 110. This relative proximal movement of the outer

O assembly 105 with respect to the inner assembly 104 exposes the stent 102 housed

M near the distal end 1 03a of the outer assembly 1 05. The released stent 1 02 then may

promote the structural integrity of the anatomical structure 191. Because the stent 1 02
may be in a compressed and elongated state within the outer assembly 105, sufficient
force must be imposed on the outer assembly 105 to initiate movement with respect to
the inner assembly 104. Such a force must overcome the countering frictional forces
caused by the relative movement of any contacting area between the outer surface of
LAW omcs the inner assem biy 1 04 and the interior surface of the outer assembly 1 05, the radial

Finnecan, Henderson, '
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i3 S oo i strewn, w. f fictional force imposed by the constrained stent on the interior surface of the outer

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assembly 1 05, and the frictional force caused by the relative movement of the outer |

assembly 105 with respect to the insertion point 192 and any other contacting surface.

j! [036] Although health care workers typically calculate the exact release point of

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the stent 102 into the anatomical structure 191 1 any movement or shift in the position of j
the stent during deployment may produce undesirable positioning of the stent 102 within
the anatomical structure 191 . Thus, it would be desirable, before the stent 102 is fully
deployed, meaning that the stent 102 has been completely released into the anatomical

i structure and its proximal end is no longer constrained within the outer assembly 105, to I

i I

be able to reconstrain at least part of the stent 1 02 back into the outer assembly 1 05 to
allow for re-positioning of the stent 102 or withdrawing the stent 102 altogether, if
necessary. Hence, during deployment of the stent 102, reconstrainment may be
initiated to detract the stent 102 at least partially back into the outer assembly 105.
Reconstrainment is performed by a relative proximal movement of the inner assembly
1 04 with respect to the outer assembly 1 05 in the direction of the arrow 1 1 0, until the \
stent 102 is sufficiently retracted into the outer assembly 105 to allow re-positioning of

j

the delivery assembly 101 in a desired position with respect to the anatomical structure
191 . Reconstrainment may also be used to retract the stent 102 into the outer

i

assembly 105 while directing the delivery assembly 101 around tight curves. After the
stent 102 is fully deployed within an anatomical structure 191 and is no longer in j
communication with the delivery assembly 101, the delivery assembly 101 may be

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; withdrawn from the patient in the direction shown in arrow 111, and completely removed '

jj

from the patient's body 1 90.

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[037] Figs. 2a-2c, as described above, have been presented to depict the
relative movement of the outer and inner assemblies during deployment and possible
reconstrainment. It should be noted that Figs 2b and 2c have been presented to show
the relative movement of the two assemblies 104 and 105 and consequent stent 102
deployment, and, for sake of clarity, have not been presented with all of the details of
Fig. 2a.

[038] To promote such a relative motion of the inner assembly 104 with respect
to the outer assembly 105 and to decrease the requisite force to induce such motion, it
is desirable to minimize any friction between the two assemblies. Furthermore, tortuous
ll pathways and other natural bends in a patient's internal anatomy may kink or bend the

p outer assembly 105, which not only may compromise the structure integrity of the stent

|i delivery device 100, but also may increase the force required to move the inner and

|nfc outer assemblies with respect to each other. Furthermore, it would be desirable for the

2 outer assembly 105 to have improved force transmission characteristics and flexibility,

□ particularly in the stent region, where flexibility would be most desirable.

H [039] Figs- 3 and 4a-4c show the outer and inner assemblies 105 and 104,

respectively, of an exemplary embodiment of an apparatus 100 of this invention. The
outer assembly 105 has been described in U.S. Patent Application Serial No.
09/569,445, which is incorporated by reference herein in its entirety. A brief review of
this outer assembly 105 will be made herein for clarity. The outer assembly 105, as
shown in Fig. 3, may have a non-braided clear distal region 105a welded at area 1 15 to
law offices a braided opaque proximal region 105c at a transitional region 105b for added kink

Finnegan, Henderson, ^ ^ ^

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,3 8 oo i street; n.w. resistance and improved force transmission. The distal region 105a may be 8 French,

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or any other dimension as long as it does not hinder movement of a stent 102 within.
The clear distal region 105a partially covers the stent 102 during insertion of the delivery
system 101 into a patient's body 190. Also, the outer assembly 105 may be any
material that is naturally flexible and biocompatible, such as polyether block amide
(Pebax), other low density polymers, or other suitable materials. The clear region 105a
allows a health care worker to observe the relative movement of the stent 102 during
deployment such that the stent is deployed in a suitable area, and the proximal end of
the stent is visible to the health care worker as the proximal end passes within the clear
region 105a before stent release. The distal end of the assemblies 104, 105 and stent
deployment may be viewed by any suitable known method, including, for example, an
endoscope with camera system, or through fluoroscopy. The proximal region 105c
! extends a substantial distance along the length of the delivery system 101 , and is
constructed of relatively stiff material, such as 72D Pebax, to maintain the strength of
the delivery system 101 . The transitional region 105b is a point of adhesion between
the flexible, clear material in the distal region 105a and the relatively stiff, strong
material in the proximal region 105c.

[040] Because the distal region 105a in the exterior tube assembly 105 may not
be braid reinforced and typically is thin walled, typically 0.006" - 0.008" width walls, for
flexibility, it may be likely to kink around a bend unless internally supported. Thus, the
inner assembly 104 may include an inner elongated structure 104b, which may be
constructed of polyetheretherketone (PEEK), having one or more jackets 104a, which
may be made of Pellethane, along its length to minimize friction when the one or more
jackets 1 04a contact the interior surface of the outer assembly 1 05. Furthermore, a

i

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jacket 104a may provide interior support to the distal exterior tube region 105a. As
shown in Figs. 4a-4c, the layer of Pellethane typically is on a shortened jacket 104a of a
conventional material, such as PEEK, used as a material for the inner elongated
structure 104b, which will be described as a tube in the illustrated embodiments. This
jacket 104a is of sufficient length to support the non-braided, clear portion of the exterior
tube 105a during, for example, reconstrainment around a curve. The jacket 104a
typically is longer than the longest constrained length of the stent 102 to provide support
for the stent 102. The combination of the inner assembly 104, having a jacket 104a with
a layer of pellethane thereon, with the outer assembly 105, results in an endoscopic
delivery system with excellent force transmission, a flexible stent region, and low
requisite deployment/reconstrainment forces in tortuous anatomies.

[041] To further inhibit friction and promote ease in operation of the stent
delivery system 100, a gap 108 may be created between the outer surface of the inner
assembly 104 and the inner surface of the outer assembly 105. This gap 108 may be
approximately 0.005", but may range from 0.004 to 0.008". The gap 108 may be
increased as the diameter of the tubes creating its walls are increased. Furthermore,
there may be a short length in neckdown to fit into the stainless steel counterbore to
support the proximal region. Such support of the proximal region is similar to a flexible
transition.

[042] The distal jacket 1 04a may be thermally attached proximal to the distal
portion of the interior tube 104b. This jacket 104a may be a length that would support a
constrained length of the stent 102, which typically is longer than its unconstrained
length. A typical length for the jacket 1 04a may be approximately 1 30 mm. However,

15

the length of the jacket 104a may be changed to accommodate stents 1 02 of different
! lengths. More particularly, the length of the jacket 1 04a may be that of the longest
| constrained stent length in order to provide internal support to the exterior tube

i

assembly 105 until the point where the stent 102 is fully deployed into the anatomical
structure 1 91 . The proximal end of the stent 1 02 may be in communication with a

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holding cup 133 that holds the proximal end of the stent 102 and a holding sleeve 104c
that is attached near the distal end of the inner assembly 104. The holding sleeve 104c
may be an opaque sheet of plastic, such as Tecothane, for example, in a distinct color,
such as red, for example, that holds the proximal end of the stent 102 and also serves
| as a visual indicator to a health care worker of the proximal end of the stent 102. The
holding sleeve 104c may accommodate the stent 102 by friction, such as by laser
'% cutting polymer from wire to create bare stent ends, and leaving silicone ribs on the

backside of the wire, thus providing a high friction surface that comes in contact with the
]| holding sleeve 104c. Additionally, during deployment, visual signal bands 131 that may

p be adjacent the holding sleeve 104c, and which may be radiopaque such as, for

H example, tantalum or platinum, may become visible through a fluoroscope through the

clear portion of the exterior tube 105a, such that a health care worker would be signaled
that the stent 102 is close to being deployed, thus if reconstrainment is necessary to re-
position the stent 102, it would be time to do so. The stent 102 is free to move
independently of the outer assembly 1 05 as directed by the inner assembly 1 04. As
discussed above, to activate deployment of the stent 102, the outer assembly 105
law orncEs typically is retracted proximally which moves the non-braided region 105a over the inner

FiNNECAN, Henderson,
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,3ooS'nw. member jacket 104a. During reconstrainment of the stent 102, the inner assembly 104

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may be pulled proximally while the exterior assembly 105 remains stationary. The low
friction response of the jacket 104a with the interior lining of the outer assembly 105
typically results in less resistance than conventional stent deployment assemblies
because there is a limited area of contact between the two assemblies. In an
exemplary embodiment, Pellethane tubing is used as the jacket 104a material and
PTFE is used as the interior surface lining of the exterior assembly 1 05. Alternatively or
additionally, the surface of the jacket 104a may be lubricated with a suitable lubricant
such as MDX silicone to further decrease frictional forces opposing relative movement
between the two assemblies. Other materials, besides Pellethane, also may be used
for the jacket 104a as long as the materials exhibit relatively low frictional forces when in
contact with the interior surface of the outer assembly 1 05. Such alternative materials
for the jacket 104a may include low-density polyethylene.

[043] Figs. 5a and 5b show exemplary embodiments of the relationship between
different components of a stent delivery device 101 , including the stent 102, outer
assembly 105, and inner assembly 104. As shown in these figures, an outer assembly
105, including a clear outer portion 105a, a transition region 105b, and a opaque
braided region 105c, surrounds an inner assembly 104, including multiple Pellethane
jackets 104a along an interior tube 104b. A holding sleeve 104c assists in holding and
identifying the proximal end of a stent 102. At the distal end of the stent 102 is a marker
band 131 that marks the front edge of the stent 102, thereby assisting in proper stent
position during deployment. The marker band 131 may be radiopaque to be visible
under fluroscopy. The lead point 1 17 is positioned distal to the marker band 131 . The
braid 139 in the outer assembly 105 may extend across the opaque region 105c and the

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transition region 105b, thereby partially covering the stent 102 held within the outer
assembly 105. Part of the stent 102, however, may be visible through the clear region
105a. As stated above, during stent 102 deployment, when the marker band 131
adjacent the holding sleeve 104c is visible through the clear region 105a under
fluoroscopy, a health care worker is signaled that the stent 102 is nearly completely
deployed and, thus, any reconstrainment to re-position the stent 102 within the
anatomical structure 191 , if needed, should be initiated. Otherwise, the stent 1 02 will be
completely deployed into the anatomical structure 191 and released from the delivery
system 101.

[044] Another exemplary embodiment of the inner assembly 104 is shown in
Figs. 6a-6c. In this embodiment, multiple contact areas, such as the three exemplary
areas shown as 104a1-104a3, project on the surface of inner tube 104b. These
multiple contact areas 104a1-104a3 function much like the jacket 104a in Fig. 4 in
communicating with the interior surface of an outer assembly 1 05. The inner assembly
104 in Figs. 6a - 6c exhibits more controlled resiliency and strength by having multiple
contact areas 104a1-104a3 that decrease in stiffness, as measured by durometer value,
as the contact areas are more distally located. Stated differently, a durometer measure
of contact area 104a1 may be less than a durometer measure of contact area 104a2,
which may itself be less than a durometer measure of contact area 104a3. Exemplary
embodiments of contact area durometer measure may be 55D for contact area 104a1 ,
65D for contact area 104a2, and 75D for contact area 104a3. This use of sequentially
increasing durometer material on an inner assembly 104 from a distal end proximally
promotes flexibility in the delivery system 101 where it would benefit greatly, near the

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distal end. The lower durometer material is more flexible than higher durometer
material. Thus, the delivery system 101 will gain in flexibility towards its distal end,
where the stent delivery device may require a greater degree of precision in winding
through tortuous anatomy. However, the structural integrity of the overall stent delivery
device 100 will be maintained because a higher durometer material is used throughout
a significant length of the inner assembly 104.

[045] Other embodiments of the invention will be apparent to those skilled in the
art from consideration of the specification and practice of the invention disclosed herein.
For example, the sequential increase in the durometer measure of subsequent contact
areas of Figs. 6a-6c may occur at every other contact area, or other such trend, as long
as there is an increase in flexibility from a proximal region to a distal region of the inner
assembly 104. Also, there may be more than one distinct jacket layer 104a of
Pellethane used in the illustrated embodiment depicted in Figs. 4a-4c, or stated
differently, each of the jacket layers 104a1, 104a2, and 104a3 in Figs. 6a-6c may be
Pellethane. More than or less than three jacket layers are possible in the illustrated
embodiment depicted in Figs. 6a-6c. Furthermore, the length of the clear region 105a
may be changed to suit the preference of health care workers so that either more or
less of the constrained length of the stent 102 may be visible during
deployment/reconstrainment. It is intended that the specification and examples be
considered as exemplary only, with a true scope and spirit of the invention being
indicated by the following claims.

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